This application is also a continuation-in-part application Ser. No. 08/794,782 filed Feb. 3, 1997 and related to U.S. application Ser. No. 09/166,816 filed Oct. 5, 1998.
1. Field of the Invention
The present invention relates to methods and apparatus for electro-optically reading symbols, for example, bar code or matrix array symbols and, in preferred embodiments, to a compact, hand held optical code reading system with multiple user actuatable functions and feedback signals.
2. Background and Objects
Code readers are known in the prior art for reading various symbols such as bar code symbols appearing on a label or on the surfaces of an article. The bar code symbol itself is a coded pattern of indicia comprised of a series of bars of various widths spaced apart from one another to bound spaces of various widths, the bars and spaces having different light reflecting characteristics. The readers in scanning or imaging systems electro-optically transform the graphic indicia into electrical signals, which are decoded into information, typically descriptive of the article or some characteristic thereof. Such characteristics are conventionally represented in digital form and used as an input to a data processing system for applications in point-of-sale processing, inventory control and the like. Scanning systems of this general type have been disclosed, for example, in U.S. Pat. Nos. 4,251,798; 4,369,361; 4,387,297; 4,409,470; 4,760,248; 4,896,026 and 5,600,121, all of which have been assigned to the same assignee as the instant application. As disclosed in some of the above patents, such systems may employ a hand held, portable laser scanning device held by a user, which is configured to allow the user to aim the device, and more particularly, a light beam, at a targeted symbol to be read.
The light source in a laser scanner bar code reader is typically a semiconductor laser. The use of semiconductor devices as the light source is especially desirable because of their small size, low cost and low voltage requirements. The laser beam is optically modified, typically by an optical assembly, to form a beam spot of a certain size at the target distance. It is preferred that the cross section of the beam spot at the target distance be approximately the same as the minimum width between regions of different light reflectivity, i.e., the bars and spaces of the symbol.
In the laser beam scanning systems known in the art, the laser light beam is directed by a lens or other optical components along the light path toward a target that includes a bar code symbol on the surface. The moving-beam scanner operates by repetitively scanning the light beam in a line, pattern or series of lines across the symbol by means of motion of a scanning component, such as the light source itself or a mirror disposed in the path of the light beam. The scanning component may either sweep the beam spot across the symbol and trace a scan line across the pattern of the symbol, or scan the field of view of the scanner, or both.
Bar code reading systems also include a sensor or photo detector which detects light reflected or scattered from the symbol. The photo detector or sensor is positioned in the scanner in an optical path so that it has a field of view which ensures the capture of a portion of the light which is reflected or scattered off the symbol. This light is detected and converted into an electrical signal. Electronic circuitry and software decode the electrical signal into a digital representation of the data represented by the symbol that has been scanned. For example, the analog electrical signal generated by the photo detector is converted by a digitizer into a pulse or modulated digitized signal, with the widths corresponding to the physical widths of the bars and spaces. Such a digitized signal is then decoded, based on the specific symbology used by the symbol, into a binary representation of the data encoded in the symbol, and subsequently to the information or alphanumeric characters so represented.
The decoding process of known bar code reading system usually works in the following way. The decoder receives the pulse width modulated digitized signal from the digitizer, and an algorithm, implemented in the software, attempts to decode the signal. If the start and stop characters and information between them in the scan were decoded successfully, the decoding process terminates and an indicator of a successful read (such as a green light and/or an audible beep) is provided to the user. Otherwise, the decoder receives the next scan, performs another decode attempt on that scan, and so on, until a satisfactorily decoded scan is achieved or no more scans are available.
Such a signal is then decoded according to the specific symbology into a binary representation of the data encoded in the symbol, and to the information or alphanumeric characters so represented. The decoded information may be stored or subjected to data processing.
Moving-beam laser scanners are not the only type of optical instrument capable of reading bar code symbols. Another type of bar code reader is one which incorporates detectors based on solid state imaging arrays or charge coupled device (CCD) technology. In such prior art readers the detector is typically smaller than the symbol to be read. Accordingly, image reduction is performed by an objective lens in front of the array or CCD. The symbol may be illuminated with light from a light source such as light emitting diodes (LED) in the scanning device, and each array cell is sequentially read out to determine the presence of a bar or a space. A code reading engine employing imager technology is disclosed in U.S. application Ser. No. 09/096,578 filed Sep. 1, 1998 and assigned to applicant herein.
It is known to provide multiple actuators in hand held optical code readers. For example, a system disclosed in U.S. Pat. No. 5,117,098, uses a multi-position trigger switch in a hand-held laser scanner. The scanner is aimed at the symbol to be scanned during a first operational state in which an aiming pattern is emitted. Once the user had aligned the scanner properly with respect to the location of the symbol, the trigger switch is actuated again to put the device into a second operational state in which the beam is scanned across the symbol in the normal scanning or reading mode, and the symbol decoded. European Patent No. 0355355 describes a combination bar code reader and EAS tag deactivator, including an embodiment with a multi-position trigger.
U.S. Pat. No. 5,600,121, assigned to applicant, discloses, inter alia a system for reading indicia such as bar code symbols having a scanner for generating a scanning light beam directed toward a symbol to be read; a first actuator manually displaceable form a first position to a second position for producing a first light beam for aiming or positioning the reader, and a second actuator manually displaceable from a first position to a second position for initiating a scanning beam pattern for reading the symbol. The actuators are independently operative of each other. A detector receives the reflected light from the symbol and produces electrical signals corresponding to data represented by the symbol. A graphical user interface simplifies system control functions.
There is a need, however, for a more compact and versatile bar code reader which is simply and inexpensively fabricated. Moreover, such a reader would be easy to use and provide user access and feedback for a broad range of functions.
Accordingly, it is an object of the present invention to provide a compact and versatile bar code reader which is simply and inexpensively fabricated.
It is another object of the present invention to provide a hand held bar code reader with an ergonomically designed shape and configuration of actuators and indicators.
It is a further object of the present invention to provide a bar code reader which provides a broad range of data acquisition, data verification and downloading functions, while being easy to use and providing feedback to the user.
These and other objects and features will be apparent from the following summary and descriptions of preferred embodiments.